Hydrometallurgical process for the recovery of nickel and cobalt values from a sulfidic flotation concentrate

Abstract

A hydrometallurgical process for the recovery of nickel and cobalt values from a sulfidic flotation concentrate. The process involves forming a slurry of the sulfidic flotation concentrate in an acid solution, and subjecting the slurried flotation concentrate to a chlorine leach at atmospheric pressure followed by an oxidative pressure leach. After liquid-solids separation and purification of the concentrate resulting in the removal of copper and cobalt, the nickel-containing solution is directly treated by electrowinning to recover nickel cathode therefrom.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
     
       1. A process for the extraction, separation and recovery of nickel, cobalt, and copper from a nickel-cobalt-copper-sulfide containing flotation concentrate comprising: 
       preparing a slurry containing said sulfide containing flotation concentrate and contacting said slurry with an oxygen and chlorine-containing gaseous stream in an atmospheric acid leach stage to thereby generate an oxidative pressure leach feed slurry containing at least about 2 to 40 g/L concentration of chloride ions therein;  
       subjecting said oxidative pressure leach feed slurry to an oxidative pressure leach under acidic conditions at a temperature ranging between about 100 to 150° C. to selectively leach the majority of the nickel, cobalt and copper therefrom to form a nickel, cobalt, copper-containing oxidative pressure leach solution and an oxidative pressure leach residue;  
       treating said nickel, cobalt, copper-containing oxidative pressure leach solution after separating the oxidative pressure leach residue therefrom, to separately recover the copper and cobalt, and to remove impurities to thereby form a purified nickel-containing leach solution; and  
       electrowinning nickel from said purified nickel-containing oxidative pressure leach solution to thereby produce nickel cathode, chlorine, oxygen and sulfuric acid therefrom.  
     
     
       2. The process according to  claim 1  comprising finely grinding said sulfidic flotation concentrate to a particulate size ranging between 6 to 30 microns prior to the introduction to said atmospheric acid chlorine leach. 
     
     
       3. The process according to  claim 1  wherein the atmospheric leach is conducted at between about 40 to 90° C. 
     
     
       4. The process according to  claim 1  including recycling at least a portion of the sulfuric acid produced in the nickel electrowinning step to the atmospheric acid leach. 
     
     
       5. The process according to  claim 1  including recycling at least a portion of the chlorine and oxygen produced in the nickel electrowinning step to the atmospheric acid leach. 
     
     
       6. The process according to  claim 1  wherein the concentration of chloride ions in the oxidative pressure leach feed slurry ranges between about 5 to 10 g/L. 
     
     
       7. A process for the extraction, separation and recovery of nickel, cobalt, and copper values from a nickel-cobalt-copper-iron sulfide containing sulfidic flotation concentrate comprising: 
       preparing a slurry containing said sulfidic flotation concentrate and contacting said slurry with an oxygen and chlorine-containing gaseous stream in an atmospheric acid leach at about 40° to 90° C. to thereby generate an oxidative pressure leach feed slurry containing at least about 2 to 40 g/L concentration of chloride ions therein;  
       subjecting said oxidative pressure leach feed slurry to an oxidative pressure leach under acidic conditions at a temperature ranging between about 100 to 150° C. to selectively leach the majority of the nickel, cobalt and copper therefrom to form a nickel, cobalt, copper-containing leach solution and an oxidative pressure leach residue;  
       separating said nickel-cobalt-copper-containing oxidative pressure leach solution from said oxidative pressure leach residue;  
       removing contained copper from said nickel and cobalt-containing oxidative pressure leach solution, neutralizing said copper-depleted nickel and cobalt-containing oxidative pressure leach solution and removing iron therefrom;  
       purifying said nickel and cobalt-containing oxidative pressure leach solution to thereby remove impurities from the nickel and cobalt-containing oxidative pressure leach solution;  
       removing cobalt from said nickel and cobalt-containing oxidative pressure leach solution utilizing solvent extraction; and  
       electrowinning said nickel-containing oxidative pressure leach solution to thereby produce nickel cathode, chlorine, oxygen and sulfuric acid therefrom.  
     
     
       8. The process according to  claim 7  comprising finely grinding said sulfidic flotation concentrate to a particle size ranging between about 6 to 30 microns. 
     
     
       9. The process according to  claim 7  comprising recycling at least a portion of the sulfuric acid generated in the nickel electrowinning step to said atmospheric acid leach. 
     
     
       10. The process according to  claim 7  comprising recycling the oxygen and chlorine generated in said nickel electrowinning step to said atmospheric acid leach. 
     
     
       11. The process according to  claim 7  wherein said predetermined concentration of chloride ions in said oxidative pressure leach feed slurry ranges between about 5 to 10 g/L. 
     
     
       12. A process for the preparation of an oxidative pressure leach feed slurry from a nickel-cobalt-copper-containing sulfidic flotation concentrate comprising: 
       finely grinding said flotation concentrate to a particulate size ranging between about 6 to 30 microns; preparing a slurry containing said finely ground flotation concentrate; and contacting said slurry with an oxygen and chlorine-containing gaseous stream in an atmospheric acid leach to thereby generate a pressure leach feed slurry containing at least about 2 to 40 g/L concentration of chloride ions therein.